The present invention relates generally to a fuel storage and dispensing system and, more particularly, to a system which employs a storage tank, a fuel dispenser, a fuel dispensing nozzle and spout, a boot, a pressure relief chamber, a filter system, and a pump to reduce the discharge of pollutants from underground fuel storage tanks, as well as the emission of hydrocarbon vapors above ground during fueling. The system is arranged to discharge pollutant free air through an air exhaust port when the pressure within the system reaches a predetermined level. Air to be discharged is separated from fuel vapor within the filter system prior to its discharge.
In addition to the capture of pollutants that are vented from underground fuel storage tanks, the petroleum industry has increasingly made provisions for recovering fuel vapors that are displaced from a vehicle fuel tank as fuel is discharged therein. Generally, there are two types of systems designed for vapor recovery—pressure balance recovery systems and vacuum-induced vapor recovery systems.
Pressure balance systems involve the addition of a vapor return conduit system that extends from a dispenser nozzle, through a hose, to a dispenser pedestal and then through an underground conduit system to a point of disposal. Most frequently, the means of disposal is simply to return the vapors to the storage tank from which fuel is drawn to fill the fuel tank of the vehicle. As fuel is withdrawn from the storage tank in fueling a vehicle, the vapor space within the storage tank is increased. Conversely, as fuel is introduced into the fuel tank of a vehicle, vapor space is decreased to essentially an identical extent. The resultant pressure differentials cause the vapors to flow through the vapor conduit system from the nozzle back into the storage tank, thereby creating a pressure balance.
Vacuum-induced vapor recovery systems employ vapor recovery lines as well as a vacuum assist to enhance the return of displaced vapors to the storage tanks. Vacuum assist nozzles also include a vapor return passage for connection with a coaxial hose, at the opposite or hose attachment end of the nozzle. However, the nozzles employed in vacuum assist systems are not without faults. The coaxial design of the nozzle is prone to dripping once fueling is complete and the nozzle is discharged from the vehicle tank inlet pipe. Such dripping can lead to significant emission of volatile organic compounds (“VOC”) into the environment. Accordingly, the present inventors have recognized a need for improvements in fuel storage and dispensing system design, which is effective in reducing fugitive emissions, as well as improvements in the design of nozzles, boots, and other associated assemblies for vacuum-induced vapor recovery systems.